The proposal will address the regulation of gene expression by glucose, which might use a conserved mechanism in all eukaryotic cells. The Snfl protein kinase complex in budding yeast, as well as its mammalian homologue AMPK, has been shown to regulate gene expression in response to glucose. The proposed study will focus on a novel gene, SMEK, which might be another conserved component mediating glucose signaling. SMEK homologues form a previously unrecognized protein family conserved from yeast to mammals. Disruption of SMEK in budding yeast (SC-SMEK) results in specific defects in glucose metabolism. Preliminary results suggest that SC-Smek may associate with the membrane glucose sensors via other proteins. Furthermore, GFP-tagged SC-Smek translocates from the membrane to the nucleus upon glucose starvation. These data suggest that SMEK may be part of a glucose sensing mechanism conserved in eukaryotic cells. This mechanism will be elucidated by addressing the following specific aims: i) Determine if yeast and human SMEK proteins are functional homologues. ii) Characterize the mechanisms responsible for SMEK nuclear translocation. iii) Investigate the role of SMEK in the regulation of gene expression by glucose. iv) Determine if SMEK is a substrate for AMPK/SnfI. It is expected that the proposed research will provide insights towards an understanding of the glucose homeostasis in mammals and pathogenesis of diabetes.